Key Aspects of Liquid Product Recovery (Pigging) Systems
Liquid product recovery (also referred to as ‘pigging’) is used after a product transfer to remove or recover residual liquid product remaining in the pipeline of a process system.
Process pigging technology has been widely adopted by food, beverage, homecare, paint, personal care, and pet food plants throughout the world. It’s an extremely effective way to increase product yields, cut waste, speed up changeover times, improve profits and boost environmental sustainability.
Hygienic (sanitary) pigging systems are made up of variety of different parts and components. Important components of pigging systems include the pipeline pig, pig detectors, launch and receive stations, pigging sequence control software and pipework. Valves are another important aspect that enable the safe and effective running of a pigging system.
This blog article looks at the valves widely used in pigging systems. Please note, this blog is specifically referring to HPS pigging equipment, products, and components designed for hygienic, sanitary and process applications. Other process pigging companies may supply valves with their pigging systems, but they may differ slightly to HPS valves in features, benefits and so on.
What are Piggable and Non-Piggable Valves?
There are various types of valves used in HPS pigging solutions. We typically categorise valves as piggable and non-piggable valves.
Piggable valves refer to the valves that enable the smooth passage of the hygienic (sanitary) pig. They have a bore the same as that of the pipe and have no obstructions when fully opened. This enables the pig, when propelled through the pipeline by either compressed air, carbon dioxide, nitrogen, water, or the next product, to easily fit through the valves.
Common types of piggable valves include sanitary ball valves, three-way diverter valves, non-sanitary ball valves, t-port valves and retractable auto pig stops.
Non-piggable valves refer to valves that do not permit the free travel of the pig i.e. butterfly valves. Although they aren’t piggable, they still play an important role in pigging systems.
Piggable Valves Used in Pigging Systems
Sanitary Ball Valves
The HPS inflatable Seal Ball Valve (ISBV), unique to HPS, has been designed specifically for hygienic and sanitary applications. It is designed so that when ready to clean, the seals can be deflated to wash the cavity and face of the ball during clean in place (CIP).
The ISBV features a full-bore design and comprises of a valve body, flanges, seals, ball, valve stem and typically an actuator for automated operation.
There are two variations of the ISBV: the 90-degree, two position ISBV and the 120-degree ISBV. The 90-degree, two position ISBV is an excellent choice for hygienic (sanitary) applications. That’s because it can be used as a line or tank isolation valve to achieve uninterrupted product flow. Alternatively, it can also be used in combination with a pig housing to create a launch or receive unit.
If chosen as a 120-degree ISBV configuration, it eliminates the need for a two valve ‘T’ launch arrangement. Instead the ISBV’s three ports can be utilised using an electrical actuator. Alternatively, the two ports can be utilised using a pneumatic actuator.
The main advantage of an HPS ISBV over a regular ball valve is that it has an inflatable seal. The seal can be inflated and deflated as required. When the ISBV seals are inflated, the seals make contact with the ball. This restricts the flow of liquid product to pass through the ball.
Likewise, when CIP is required, the seals are deflated. Deflating the seals ensures they are no longer in contact with the ball. This creates a path around the face of the ball and the cavity. Therefore, the liquid product is free to flow through it and clean previously unreachable areas.
Three-Way Piggable Diverter Valves
The Solid Seat Ball Valve (SSBV) is a three-way piggable diverter valve. The valve rotates between ports allowing non-obstructed product transfer. This can be from one source to two selectable positions, or from two selectable product sources to one destination.
The innovative and robust design of the SSBV provides optimum efficiency for liquid product recovery (pigging) situations. The valve enables easy diverting of a pipeline pig used to reclaim and recover residual product from the pipeline or tubing. The HPS hygienic (sanitary) pig can easily pass through the valve and recover up to 99.5% of product. It can also be used in process systems without pigging to aide process routing.
Alternatively, HPS piggable diverter valves can be used as pig launchers. To utilise the SSBV as a pig launcher, the valve should be attached to the outlet port of the pump.
By doing this, product can pass through a full-bore path while in the transfer position. And when the transfer is complete, the SSBV will rotate to the pig launch position. This opens a path for the HPS pig to enter the transfer line and blocks the path from the pump outlet port.
T-Port Piggable Valves
HPS T-port valves have been designed and precision-engineered by our pigging system experts to offer high performance, robustness, and a long working life.
T-Port valves are commonly used in pigging systems to divert liquid product from the straight path of a transfer line.
The innovative and piggable design of the valve features a t-port internal through path. This enables the HPS process pig to push the product through the pipe to its destination.
T-port valves can also divert product at 90-degrees. However, valves in this configuration are not piggable.
HPS ball valves offer high performance with easy installation. They are used in HPS pigging systems to either stop product or the pig in a piggable line.
Ball valves are particularly suitable for hygienic and sanitary applications such as food and beverage processing as well as high velocity applications. They have a cavity filler to remove the build up of product behind and on the face of the ball.
Because ball valves have the same bore as the pipeline, this enables the HPS pig to travel smoothy through the valve.
Retractable Auto Pig Stops
Auto pig stops consist of a specialist pin that goes in and out of the line. They can be used in a pigging system to stop the pig at a particular point, while allowing liquid product to pass freely.
Non-Piggable Valves Used in Pigging Systems
Butterfly vales are a cost-effective valve commonly used in liquid product recovery systems to isolate or regulate the flow of fluid. Because they are not piggable, they are often used in areas where the pig does not travel, for instance tank inlets and outlets.
With a simple and elegant design and engineered to be robust and extremely reliable, butterfly valves are frequently used in a wide range of applications requiring extensive product passage. Butterfly valves can be supplied as both manual and pneumatic actuator options.
Which Valve Can Be Used in Which Area?
Non-piggable valves are typically used at the outlets of launching and receiving stations or for the propellent supply. Because they are not piggable, they are not used inside of piggable pipelines.
On other hand, piggable valves such as the three-way diverter valves and sanitary ball valves are typically used in the launch and receive stations of the pipeline.
HPS Product Recovery Solutions are the world’s leading provider of pigging equipment, components and services for the food, beverage, pet food, homecare, paint, coatings, personal care, and cosmetics industry.
With more than 25 years of experience and a proven track record, HPS are committed to offering the highest quality pigging products as well as unrivalled customer care (here’s more about why you should consider choosing HPS Product Recovery Solutions).
Whether you want a quotation for a valve or other spare part for your pigging system, have a technical question or have a new pigging or liquid transfer project, our team are here to help: